Synthetic filament, such as polyester and nylon, is applied with a finish just after being extruded from spinnerets for the purpose of eliminating broken filament and ends down in yarn production and processing, passing the filament through the processes easily and being processed into high quality textile products.
Especially, the finishes applied in the spinning process of polyester or nylon filament to be processed into textured yarn or industrial textiles are required to be thermally durable because such filament is exposed to heat on heater rolls or plates in yarn production, texturing or further processing stages. The thermal durability mentioned here is a special property of finishes that do not easily decompose to change into fume during a short time heating and decomposes easily during a long time heating not to remain as tar buildup on heater rolls or plates. In addition, the finishes for polyester or nylon filament to be processed into textured yarn or industrial textiles are also required to impart superior lubricity, antistaticity and yarn winding performance to filament at high temperature for the purpose of minimizing ends down, broken filament and deposit in yarn production and processing, passing filament easily through yarn production and processing stages and producing excellent textile products.
Recent increase of yarn production and processing speed and demand for high-quality textile products resulted in the increase of the temperature of heater rolls or plates and consequently the demand for finishes that do not generate fume or tar buildup mentioned above has been increasing. In addition, the increase of the processing speed has accelerated the demand to finishes to impart lubricity, antistaticity and yarn winding performance at high temperature.
Furthermore those finishes are expected to be biodegradable because they are washed with water before yarn is processed into end products and the washed off finishes are treated in the wastewater.
In the conventional processes, the polyester or nylon filament to be fed to texturing process has been applied with finishes of which major component is ethylene oxide/propylene oxide block or random copolymers having 1,000 to 20,000 molecular weight and containing ethylene oxide and propylene oxide from 9:1 to 1:9 mol ratio.
The above copolymers do not easily decompose to change into fume during a short time heating but easily decompose during a long time heating not to remain as tar buildup on heater rolls or plates. They are commonly used even at present owing to their superior lubricity and antistaticity at high temperature.
However, the above copolymers has poor biodegradability and cannot meet the demand for the recent high-speed process and high quality textile products because of their unacceptable yarn winding performance and insufficient lubricity and antistaticity at high temperature.
Thus a finish for synthetic filament that causes neither fume nor tar buildup in high speed and high temperature process, imparts superior lubricity, antistaticity and yarn winding performance to filament and is biodegradable is required.
For solving the above problem, WO 95/21956 suggests polyether polycarbonate produced by reacting polyether and dialkyl carbonate as a biodegradable lubricant. However, the reaction proceeds inefficiently and the target compound cannot be produced in high yield.
In addition, U.S. Pat. No. 4,169,062 suggests a glycol monoester of ethylene oxide/propylene oxide random copolymer and fatty acid as a water-soluble and biodegradable lubricant for synthetic fiber. However, the lubricant causes tar buildup and stain on heaters at high temperature.